Initial Statement: Pediatric cancer is more rendering to the life of that particular person because as a child one has not established a life or a meaning to self-fulfill.
Mr. Martin Edit:
  • Not only battling the disease
    pediatric cancer has a _ effect on a developing young person in terms of emotional and psychological development.

Ashley Edit:__ Pediatric Cancer has a drastic [devastating] effect on a developing young person in terms of both emotional and psychological development.

Sounds better. You may still need to work with the wording a bit. Let's not repeat the word development.

Pediatric Cancer has a drastic effect on the growth of a young person in terms of both emotional and psychological development.